Ring carrier for light alloy pistons

ABSTRACT

Ferrous ring carriers for internal combustion engine pistons are provided and include an annular land formed by a flange of the ring carrier which is adjacent to the skirt end of the piston. The preferred location for the ring carrier is nearest the head of the piston.

United States Patent [191 Schieber [54] RING CARRIER FOR LIGHT ALLOY PISTONS -[75] Inventor? Gerhard Schieber, Bad Wimpfen,

Germany [73 Assignee: Karl Schmidt GmbH, Neckarsulm,

Germany 221 Filed: Jan. 14,1971

21 Appl.No.: 106,467

[30] Foreign Application Priority Data Feb. 7, 1970 Germany ..P 20 05 662.6

[52] US. Cl. ..123/l93 P, 277/1895 [51] Int. Cl. ..F02f 5/00, F16j 9/22 [58] Field of Search ..277/189.5;

[4 1 May 29, 1973 [5 6] References Cited UNITED STATES PATENTS 2,550,879 5/1951 Stevens, Jr ....277/189.5 X 2,255,006 9/1941 Graham ....277/l89.5 X 2,024,058 12/1935 Oubridge ..277/189.5 2,731,313 1/1956 Walker et a]. ..277/l89.5 X

Primary Examiner-Arnold Rosenthal Attorney-Burgess, Dinklage & Sprung [57] ABSTRACT Ferrous ring carriers for internal combustion engine pistons are provided and include an annular land formed by a flange of the ring carrier which is adjacent to the skirt end of the piston. The preferred lo.- cation for the ring carrier is nearest the head of the piston.

1 Claim, 2 Drawing Figures PATENTED M91913 3,735,746

lave/liar:

BUQGESS, bmmm firm 1 RING CARRIER FOR LIGHT ALLOY PISTONS BACKGROUND This invention relates to a light alloy piston for internal-combustion engines comprising a ring carrier of ferrous material preferably located adjacent the piston ring groove nearest the head of the piston.

To increase the service life' of light alloy pistons for internal-combustion engines, they are provided with ring carriers of wear-resistant ferrous material in which the ring grooves are formed by recess turning or grinding. In these pistons, the piston rings are embedded in the wear-resistant carriers and are thus subjected to less elevated temperatures. In most cases, the ring carriers are cast into the piston blank so as to form a metallic bond therewith.

Efforts toward an increase of the service life of a light alloy piston by the provision of ring carriers cast into the piston are directly opposed to the efforts toward an increase of the speed of the engine and a reduction of the overall height of the engine because the use of ring carriers increases not only the weight of the piston but also the height of the annular land between the ring carrier and the ring groove below the ring carrier so that the length of the ring section of the piston is increased too. For a piston having a given length and a given distance from the edge of the piston head to the uppermost ring groove, a larger length of the ring section of the piston means a reduction of the length in which the skirt of the piston is guided. A guidance of the skirt of the piston in a shorter length increases the tilting angle and results in a less smooth running and possibly in cavitation at the cylinder and in an increased wear on all sliding surfaces of the piston.

To reduce the length of the ring section of the piston, it has been proposed to so design the ring carrier that it can be formed with two or more ring grooves (W. D. Bensinger and A. Meier: Kolben, Pleuel and Kurbelwelle be schnellaufenden Motoren; Berlin, Gottingen,

Heidelberg, 1961, page 11). In this case, the reduction of the height of the annular lands and the resulting reduction of the length of the ring section of the piston is accompanied by a considerable increase of the weight of the piston.

SUMMARY THE DRAWING FIGS. 1 and 2 are partial sectional views of three embodiments of ring carriers of the present invention.

DESCRIPTION According to a special feature of the invention, the annular land is formed by the ring carrier in such a manner that, viewed in a radial direction from the periphery of the piston, at least percent of that end face of the annular land which faces the skirt end of the piston consists of the material of the ring carrier.

Because the finish recess turning of that ring groove which has one end face consisting entirely or partly of the material of the ring carrier and another end face consisting of the material of the piston body requires the use of special ring groove-turning tools and cutting speeds, it is a further feature of the invention that that end face of the annular land which faces the skirt end of the piston is coated with a layer of light alloy in a thickness of up to 2 percent of the diameter of the piston so that the conditions for machining are optimized.

Embodiments of the invention are shown by way of example in the drawing and will be explained more fully hereinafter.

FIGS. 1 and 2 show respective embodiments and consist each of a fragmentary longitudinal sectional view showing a portion of a piston l which is made by chill casting from the alloy AlSil2CuNiMg and has a head into which a ring carrier consisting of a special austenitic cast-iron has been cast adjacent to the uppermost ring groove and so as to form a metallic bond.

In FIG. 1, that flange of the ring carrier 2 which is disposed adjacent to the skirt end of the piston forms the annular land 3. In FIG. 2, the flange of the ring carrier 2 is designed so that, viewed in a radial direction from the periphery of the piston, about 70 percent of that end face of the annular land 3 which faces the skirt end of the piston consists of the material of the ring carrier.

The advantage afforded by the invention resides particularly in that the overall height and the weight of the piston are appreciably reduced whereas the length in which the skirt of the piston is guided is preserved.

What is claimed is:

1. Light alloy piston for internal-combustion engines comprising a ring carrier having an annular land which together form the piston ring groove nearest the head of the piston, said annular land having a face which faces away from the piston head and forms a wall of the next adjacent ring groove, the remaining walls of said next adjacent ring groove being formed by the material of the light alloy piston, at least 70 percent up to percent of said face consisting of the material of the ring carrier.

a n: w a 

1. Light alloy piston for internal-combustion engines comprising a ring carrier having an annular land which together form the piston ring groove nearest the head of the piston, said annular land having a face which faces away from the piston head and forms a wall of the next adjacent ring groove, the remaining walls of said next adjacent ring groove being formed by the material of the light alloy piston, at least 70 percent up to 100 percent of said face consisting of the material of the ring carrier. 